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✅JSON Validator
Validate JSON syntax and structure
Input
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Output
Processed result appears here.
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What is a JSON Validator?
A JSON validator checks whether a JSON string conforms to the RFC 8259 JSON specification — correctly structured keys and values, proper use of quotes, commas, brackets, and braces. It reports the exact location of any syntax error so you can fix it quickly without scanning hundreds of lines manually.
Why Use Utilo's JSON Validator?
Instantly validate JSON and get a clear valid/invalid result
Error messages show the exact line number and character position of the issue
Works on very large JSON files without lag
100% private — no data leaves your browser
No login or account required
Pair it with the JSON Formatter to fix and beautify in one workflow
Free and unlimited
Frequently Asked Questions
The most common causes: trailing commas after the last item in an array or object, missing quotes around property keys, single quotes used instead of double quotes, unescaped special characters in string values, and mismatched or missing brackets.
Yes. The validator runs in your browser and can parse large JSON files efficiently without sending data to a server.
Completely. All validation happens locally in your browser. No JSON is transmitted or stored on our servers.
No. Our validator checks standard JSON per RFC 8259, which does not allow comments or trailing commas. For JSON5 files, remove non-standard elements first.
Validation checks whether the JSON is syntactically correct (valid/invalid). Formatting beautifies valid JSON by adding indentation and line breaks for readability.